I think the only one we can safely eliminate is Null since he contributes actual code to the site and seems to use the same account for both, or at least he did when he was a regular.
I didn't disappear anywhere just a programming project and school doesn't leave me much free time. And technically speaking I haven't contributed any code to the site yet.
Has anyone ever thought that twicker could care less about actually taking part in the site? Or, if he is taking part in it, has anyone ever thought that he may not actually be replying to or with code but just posting to the Lounge? It really depends on what kind of person twicker is and it appears no one actually knows him in real life.
At least he keeps the site on topic in that it is all C++. Look at Moosader.com, it is a game dev site with forums but she talks about becoming a licensed HAM Radio operator now and learning Estonian (neither of which are game dev related).
So I guess it may be a good thing that twicker doesn't take part in the forums. He may turn out to be a great guy, or on the extreme opposite, turn out to be a guy that offends everyone and drives users away. I think the mystery around him should stay there and not be picked apart. Once you remove the mystery and get to know the person, you may find you don't like them and avoid interaction with them.